Most Avons are made of Hypalon - at least the ones I have ever seen. Maravia's are made of PVC and newer ones are coated with polyurethane.
For the Avon - if the floor is considerably worn down you could consider a new layer of material. You have a few main choices - cut out the existing floor, get a big sheet of hypalon and glue in a new floor. This isn't actually that difficult of a project, but the cost of all that hypalon does add up, and it would take some skill. You could also just glue a big sheet of new hyplaon to the existing one - that wouldn't be my first choice. You would add a lot of weight to your boat, but you could do it.
The next main option is adding a layer of Glacoflex to your floor. This is the best option unless your floor is quite heavily damaged (more holes that hypalon). you can get it here:
Gacoflex Hypalon® Paint
For the pinhole leaks in your Maravia you can try:
Raft Sealant Kit
I haven't used the sealant or know anyone that has experience with it - so try at your own risk. But it is probably a quality product.
Final note - with bucket boats a lot of the holes in the floor are often caused when the floor gets pinched between some thing hard, like a rock, and something hard in the boat, like a dry box or cooler. So if you are carrying those things in your bucket boat, and you have a frame, you should consider suspending them from your frame.